Yarn severing device for circular knitting machines



Aug. 20, 1963 G. BlLLl ETAL YARN SEVERING DEVICE FOR CIRCULAR KNITTING MACHINES Filed Feb. 15, 1961 Arr 3 United States Patent 3,160,977 YARN SEVERING DEVICE FOR CIRCULAR KNITTING MACHINES Giorgio Billi, Viale Torricelli 23, and Vinicio Luchi,

It is known that in circular knitting machines, the yarn is severed when a yarn guide has been raised to interrupt the yarn feed to the needles. In some circular hosiery knitting machines, it is particularly, advantageous that the yarn severing occurs in the immediate vicinity of the needle cylinder, so as to leave the shortest possible cut end of yarn on the fiabric and thereby reduce subsequent handling of the :fabric.

The present invention provides a circular knitting machine having a yarn severing device, said device comprising first and second rotary elements having cooperating circular cutting edges which are arranged to engage one another to sever the yarn extending between a raised yarn guide and the needles.

According to features of the invention, the planes containing the cutting edges are inclined at a large angle to one another, and the second one of said rotary elements is formed by a slightly cupped disc disposed in a plane substantially normal to the plane of the first of said rotary elements, a part of the cutting edge on one side of the rotational axis of the second element extending beyond the cutting edge of the first element to ensure contact between the two cutting edges.

Furthermore, the rotational axis of the second element is inclined to the diametral plane of the first element so that the cutting edges engage each other at a single point and the second element is urged resiliently against the first element to ensure contact between their cutting edges. The first element is drivingly connected with the rotary plate supporting the sinkers of the machine and the second element is driven through frictional engagement with the first element.

The invention will be better understood from the following particular description and the accompanying drawings of one embodiment of the invention. In the drawings:

FIG. 1 is a diagrammatic radial section through the cover of a circular knitting machine;

FIG. 2 is a corresponding diagrammatic plan view;

FIG. 3 is a sectional view of part of the machine of FIG. 1, the sectional plane being vertical and passing through the axis of the machine and the vertical disc;

FIG. 4 is a part sectional view taken along the line IVIV of FIG. 3.

As is diagrammatically illustrated in the accompanying drawing, the machine comprises needles 1 which rotate with the needle cylinder 4, and yarn guides 2 (diagrammatically shown in FIG. 2). A stationary circular cover 3 overlies the needle cylinder 4, and beneath this cover is a rotary plate 5 provided with the grooves which accommodate welt hooks 6. FIG. 2 indicates the zone 17 where the yarn is to be severed. This yarn is held by the last needle which has engaged it before lifting of the corresponding yarn-guide, and the yarn extends between the yarn-guide and the zone 17, and the end of it may subsequently be picked up by a suction nozzle at the 3,100,977 Patented Aug. 20, 1963 "ice month of a suction pipe 9 which will retain the severed end of the yarn until, upon lowering the yarn-guide, the yarn is once again fed to the needles.

In a recess 12, in FIG. 3, harmed by the members 3 and 5, an annular element 13 is fitted land to which is attached a second annular element 14. This second annular element forms an annular groove for accommodating a first cutting member in the form of :a fiat ring 15, the upper circular edge of which is the cutting edge. This ring is pressed against the assembly 5, 6 by spring fins 16a, which are integral with a ring 16 which engages the lower surface of the annular element 13. The cutting ring 15 is held by friction on rotary portion 5, 6 of the machine being pressed thereon by the resilient fins or tags 16a or by other equivalent spring means. The rotational speed of cutting ring 15 will be substantially equal to the speed of the rotary plate 5.

A support 18 is mounted on the cover 3 and forms a sliding seating tor a sleeve 19 whose axis is substantially parallel to the plane of the member 15 but is inclined by a small angle a (FIG. 2) with respect to the diametral plane of the ring 15. A stub shaft 20 is freely rotatable in the sleeve 19 and supports at its outer end a disc 21. The inner face of this disc is recessed :as shown at 21a (see FIG. 3) and the inner edge of the disc 21 forms a cutting edge. A spring 22 acts between the support 18 and the sleeve 19 to urge the stub shaft 20 and hence the disc 21 towards the cutting ring 15. The cutting edge of the disc 21 has a radius slightly greater than the distance between the axis of the shaft 20 and the cutting edge of the ring 15, so that the lower portion of the cutting edge of the disc 21 extends below the cutting edge of the ring 15. By reason of this arrangement and the inclination of the axis of the stub shaft 20 with respect to the diameter of the disc 15, aswell as the convexity of the disc 21, the outer cutting edge Off the ring 15 extends into the cavity 21a, and the two cutting edges intersect rat the point P in FIG. 4 through which the yarn to be cut will pass.

By reason of Contact pressure maintained between the disc 21 and the rotary ring 15 by the spring 22, the disc 21 is rotated. In order to stop the rotation of the disc 21 a bell crank lever 23 is pivoted at 24 and is urged by a control rod 25 to push the stub shaft and hence the disc 21 outwardly against the pressure of the spring 22.

When a yarn which extends between a needle moving along a circular path adjacent the peripheral outer rim of the ring 15 (and the yarn-guide 2 which is raised, reaches the severing zone 17, this yarn is inserted between the cutting edge of the ring 15 and the cutting edge of the disc 21, the yarn is severed at P by the relatively moving cutting edges, which act as continuously operating scissors. The severed end of the yarn extending from the yam-guide 2, is held in a known manner either mechanically or by suction within the nozzle 8. The severed length of yarn which extends from the fabric is very short owing to the closeness of the severing point P to the needles which is a [feature of this arrangement.

While we have shown and described what we believe to be the best embodiments of our invention, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

V What we claim is 1. A yarn severing device for a circular knitting machine including a rotatable needle cylinder oarrying a plua slightly cupped disc, the plane of rotation of the second rotary element being'suhstan tially normal to the plane of rotation of the finst of said rotary elements, a part of the cutting edge on one side of the axis of rotation of the second rotary element extending beyond the cutting edge of the first element to ensure contact between thetwo 15 cutting edges. s

2. A device according to claim 1 wherein the first rotary element has a diametral plane perpendicular to the plane of rotation of the first rotary element, the axis of rotation of the secondrotary element being inclined to the diametnall plane of the first rotary element. 7

t 3. A device according to claim 1 wherein said finst rotary element is formed by a flat ring whose outer edge is the cutting edge.

References Cited in the file of this patent UNITED STATES PATENTS 123,605 Ayres et a1. Feb. 13, 1872 1,671,597 Lengel Nov; 12, 1921 2,952,148 Rather Sept.'13, 1960 

1. A YARN SEVERING DEVICE FOR A CIRCULAR KNITTING MACHINE INCLUDING A ROTATABLE NEEDLE CYLINDER CARRYING A PLURALITY OF NEEDLES AND RAISABLE GUIDES FOR YARN FED TO THE NEEDLES, COMPRISING: FIRST AND SECOND ROTARY ELEMENTS HAVING COOPERATING CIRCULAR EDGES ENGAGING ONE ANOTHER TO SEVER YARN EXTENDING BETWEEN A RAISED YARN GUIDE AND THE NEEDLES, SAID ELEMENTS BEING ROTATABLE IN INTERSECTING PLANES, THE SECOND ONE OF SAID ROTARY ELEMENTS INCLUDING A SLIGHTLY CUPPED DISC, THE PLANE OF ROTATION OF THE SECOND ROTARY ELEMENT BEING SUBSTANTIALLY NORMAL TO THE PLANE OF ROTATION OF THE FIRST OF SAID ROTARY ELEMENTS, A PART OF THE CUTTING EDGE ON ONE SIDE OF THE AXIS OF ROTATION OF THE 